Ive gota buy one and soon....Give me the skinny on the what you believe is the best system for a ranch ICF home in COLD climate.

Watch the watts. Make sure to select an HRV with ECM motors, some older models can cost you more in electricity than the $ of heat they recover.

Venmar EKO is very low watts/CFM, 54W max. http://www.djsonline.com/venmarekotech.pdf A Lifebreath 195ECM is up to almost 100W at high speed, but still better than most. The Fantech's can draw up to ~150W. The dual core systems can be especially bad, even though they can advertise high recovery %.

Zehnder US is starting to distribute their Swiss 90%+ efficient HRVs here, but they are almost $2k. http://www.comfosystems.com/index.php?pageID=69

Those Venmar EKO's are a bit pricey i believe, and then you also have to buy another $500 air handler for them if you arnt going to be able to hook them up to a current system.

My Ultimate Air DX200 is working great. The controller adjusts the speed up to a max of 200 CFM. A timer is available to run the unit intermittently. Biggest downside is noise. At full speed it puts out a pretty good whine which is carried through the duct. I plan to replace about 20' of steel duct with flex duct to see if that cuts the noise.

The main reason I bought the Ultimate Air is it's the only one I found that has provision to work in an economizer mode. IOW, it can be switched so if the incoming fresh air is less than about 65°F the heat exchange wheel stops. During cool summer nights this helps to cool the house, cutting down on AC load. I have the unit wired to a two stage AC thermostat. The first stage puts it into economizer mode, the second stage kicks it into boost, or full speed, mode. It isn't a cheap unit, about $1800.